The analysis of the change in the structure and properties of refractory concrete impregnated with SiO2 sol

Abstract

The results of research into alumina cement based fireclay refractory concrete obtained by using the standard physical and mechanical test methods (EN ISO 1927-6), as well as XRF, SEM, EDS, MIP analysis methods are presented. Alkali resistance was tested according to ASTM C 454–83 and thermal shock resistance was tested according to DIN 51068. The research showed that alkali resistance of conventional cement castable (CC) as well as medium cement castable (MCC) products can be improved by adding fine-grained quartz and further improved by SiO2 sol vacuum impregnation. Impregnated refractory concrete has lower porosity and higher compressive strength. However, impregnated refractory concrete becomes more brittle and thermal shock resistance of such castable may decrease depending on the porosity, deformations and internal stresses of the material at high temperatures. It was found that the thermal shock resistance of SiO2 sol impregnated CC increased about 11%, whereas the penetration of potassium carbonate into the test samples reduced about 20% compared to the control samples. In the case of MCC, however, the porosity of which is lower than the porosity of CC and reduced even more after SiO2 sol impregnation, the thermal shock resistance decreased about 70%.